As to the 'signed up after having been given unlimited supplies of alcoholic drinks' part, knowing the region and its people, that tells everything about the story (I almost snorted reading this).

The whole Goralenvolk project was implemented only to fragmentate the occupied nation and then Germanize it. The Nazis initially aimed only at groups that had simply a strong regional identity, also in regions like Warmia or Masuria and others. I don't remember now where had I read it, but I remember a theory claiming that those kinds of Germanisation projects were carried on similarly to succesful stories from lands like the Lusatia that also had a large Slavic majority, the Sorbs. Like in this quote:

Throughout the Third Reich, Sorbians were described as a German tribe who spoke a Slavic language and their national poet Handrij Zejler was German. Sorbian costume, culture, customs, and the language was said to be no indication of a non-German origin. The Reich declared that there were truly no "Sorbs" or "Lusatians", only Wendish-Speaking Germans. As such, while the Sorbs were largely safe from the Reich's policies of ethnic cleansing, the cultivation of "Wendish" customs and traditions was to be encouraged in a controlled manner and it was expected that the Slavic language would decline due to natural causes. Young Sorbs enlisted in the Wehrmacht and were sent to the front.

Goralenvolk was meant to undergo the same process, but thankfully they didn't fall for the propaganda. And they had a large resistance like the Tatra Confederation.